The clause traces back to Lallana's days as a Cherries academy player when he was 10 years old, leaving for St. Mary's before he had even hit age 13, but Bournemouth clearly saw some potential in their youngster's ability.

Luke Shaw is another big-money Saints target for the Red Devils, the club having seen the reputations of several star figures rise considerably this term. However, BBC Radio Solent (h/t Sky Sports) quoted club director Hans Hofstetter—who arrived in the wake of Nicola Cortese's departure as chairman—as hinting in March that the club have no intentions to sell:

We have a very strong squad and we are still in a situation where we are free enough to act quickly if quick action is asked from us. Whilst I perceive that we have inherited a difficult situation financially, there are now clear and structured plans in place to progress the club and avoid a similar situation from occurring again.

In the short time I have been at Southampton it has become abundantly clear that we are blessed with a staff that has all the necessary skills with which to progress, and now that we can supplement that with a strong board I am sure we will enjoy a successful future together.

These latest revelations surrounding Lallana's potential purchase only further complicates a deal which looked as though it would be a difficult one to pull off irrespective of any underlying additions.

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Under Mauricio Pochettino, the south coast outfit have developed a stoic and united front like never before, with players like Jay Rodriguez, Rickie Lambert, Shaw and Lallana each helping one another in deflecting talk of their respective departures.

Of course, United would be fortunate to get their hands on the services of the wide man. OptaJoe shows Lallana was one of Southampton's more impressive figures in this weekend's 0-0 draw at Aston Villa, while Squawka point out some of his more long-term value this season:

Capable of playing just about anywhere across the midfield line, the versatile England international is a throwback to the wide midfielders of days gone by. Players whose game was focused out wide but didn't necessarily exclusively rely on hugging the touchline.

It would be folly to say a sell-on fee rules out the chances of David Moyes' side plumping for the player, though. Theoretically, if Southampton were looking for a £20 million sum, which we now know £5 million of which would go to Dean Court, United need only increase their offer by several million in order to make up the difference.

It may sound frivolous to speak of such numbers so freely, but if a club of Manchester United's stature are enthused enough in luring the playmaker to Old Trafford, these are the terms that must be accepted.

Alternatively, the Premier League giants could look to reimburse Bournemouth through alternative means. Whether that refers to a ticket-selling friendly being set up in the future, or through the promise of some loan agreement(s), United may seek to dodge a direct payment via another more cost-effective route.

By all means, this sell-on fee isn't likely to end speculation between Manchester United and Adam Lallana, but it does throw a substantial spanner in the works.